The signal to noise ratio (SNR—in speech recognition, essentially the ratio of the speech component of an acoustic input to the background noise component) is known to impact the accuracy of speech recognition engines. In many applications employing speech recognition, users have little or no control over their acoustic environment, and cannot alter the background noise level to suit their purposes.
U.S. Pat. No. 5,692,059 proposes a two active element in-the-ear microphone system as a possible mechanism for reducing noise levels. However, the '059 patent seems to suggest simply combining the signals from each active element to create a composite signal, which would then be output for use by speech recognition and communication systems.
U.S. Pat. No. 7,120,477 discloses the use of ear microphones (as one of several types of sensors) to increase speech recognition accuracy by outputting a signal indicative of whether a user is speaking. However, the '477 patent only uses data from the ear microphone to identify the starting and ending points of a speech event.